Today we are going to take a deep dive into the Adjustable Anchor Webbing and it's various usage cases. In 2014, we released this webbing in a different form. The single line strength of the first version was rated at 44 kN (10,000 lbf). This webbing was a very special item that required a unique type of webbing loom to manufacture. There are only two of these machines in the US and one of them has been decommissioned from making this specific product. It was literally destroying the machine due to the extreme thickness and dense weave the item had. The second machine is with another company and the manufacturing price is 4x as high with this vendor.

Original Adjustable Anchor Webbing

Due to these circumstances, we had to try and find a new way to make this webbing. Instead of weaving it on a special double-head shuttle loom, we switched to a needle loom construction, which is far more efficient, fast, and quite a bit more cost beneficial. However, there is a limitation on how many fiber ends can go on this machine. As such, we had to reduce the single line strength down to 33 kN, which is still high enough for most of our applications. We were able to achieve a strength on the anchor loops that was nearly identical to the first version, which is one of the most important parts of this webbing.

New Adjustable Anchor Webbing

With this new version, we wanted to test the various configurations that the adjustable anchor webbing is most commonly used in. Below we will explore 10 configurations and 3 samples each (except for two configs).

Baseline - Alpine WebLock

Normally, to test a webbings baseline strength, we rig it between two of our MONSTER Lock's, with each one rotated 180-degrees to give the webbing an even stretch profile through the thickness. However, since the Adjustable Anchor Webbing is over an inch wide, it will not load in the ML properly. As a result, our baseline test is done using the Alpine WebLock 3, which has a circular diverter, giving an even loading profile on the webbing.

Each weblock is rotated 180-degrees from each other so that the webbing wraps in opposite directions at each end. This is so there is an even elongation through the thickness of the webbing. If both ends were oriented the same way, the outer fibers in the weblock will stretch more than the inner ones, causing a premature break. This is exagerated when samples are short in the break test machine as that difference in stretch can be a significant percentage of the full length.


Sample 1 - 31.91 kN (7,174 lbf)

Sample 2 - 32.88 kN (7,390 lbf)

Sample 3 - 33.73 kN (7,581 lbf)

Average - 32.84 kN (7,382 lbf)

Standard Deviation - 0.91 kN (204 lbf)

All samples broke in the weblock

Test 1 - Slot Strength

One of the most important features of the Adjustable Anchor Webbing is the slots - the openings along the length that allow you to clip at various points in the sling. In our field, we use this for anchor slacklines to trees, personal anchors, and anchoring various other items. Having a strong slot strength has a big impact on the usability of this material and is the basis of a lot of other configurations that are very useful.

To test this, we rigged the Adjustable Anchor Webbing (a 1 meter piece) from slot to slot. The slots were connected to the pin of a 16mm Van Beest Anchor Shackle, which has a 19mm pin. We used such a large shackle as we did not want to burn through shackles with each test. A lot of 12mm shackles will see their pins start to bend at a round 15 - 20 kN, so we wanted to avoid that. As a disclaimer, this large pin may skew our results slightly in the upper direction.

Slot Strength


Sample 1 - 16.38 kN (3,682 lbf)

Sample 2 - 16.92 kN (3,803 lbf)

Sample 3 - 16.68 kN (3,749 lbf)

Average - 16.66 kN (3,745 lbf)

Standard Deviation - 0.27 kN (60 lbf)

Slot Strength Result

All samples ripped open the slot that was anchored on one layer.

Test 2 - Slot to Slot Basket

Probably the most common way to use the Adjustable anchor webbing is to wrap it around a tree and clip two slots, resulting in a "Basket" configuration. This configuration gives a lot of flexibility in how long your sling is, which is great if you use different trees in different sessions.

To test this, we wrap the anchor webbing around the pin of the large van beest shackle on one side and then connected each end to it's own shackle on the other side. We used 12mm shackles for this test as they fit better in our machine clamp.

Basket Slot Configuration


Sample 1 - 31.47 kN (7,074 lbf)

Sample 2 - 30.25 kN (6,799 lbf)

Sample 3 - 30.88 kN (6,941 lbf)

Average - 30.86 kN (6,938 lbf)

Standard Deviation - 0.61 kN (137 lbf)

Basket Slot Configuration results

All samples ripped open the slot that was anchored on one layer.

Test 3 - Girth-Hitched Slot

Another common use-case for the Adjustables is wrapping the sling around a tree and passing one end through a slot to form a girth hitch. This is useful for keeping the sling in place, or providing a focal point that is very close to your anchor for optimum swing (rodeo line anchor, for example).

To test this, we wrapped the sling around the drum on a MONSTER Lock and passed one end through a slot. On the other end, we anchored it to an AWL3 for max strength retention in order to ensure the sling breaks where we wanted it to.

Girth Hitched Slot


Sample 1 - 18.20 kN (4,090 lbf)

Sample 2 - 16.51 kN (3,711 lbf)

Sample 3 - 17.86 kN (4,015 lbf)

Average - 17.52 kN (3,939 lbf)

Standard Deviation - 0.89 kN (200 lbf)

Girth Hitched Slot Results

All samples ripped open the slot was used for the girth hitch.

Test 4 - Woven End Loop - No Stopper Knots

One of the coolest configurations that is possible with this sling material is a woven end loop. This is where you pass one ond of the sling through a number of the slots in order to form a loop at the end. In this test, we tried 4 different methods for this:

- A woven end loop with just 3 pass-throughs

Three pass-through method

- A woven end loop with 4 pass-throughs

Four pass-through method

- A woven end loop with 5 pass-throughs

Five pass-through method

- A woven end loop with 6 pass-throughs

6 pass-through woven end loop

The 3 and 4 pass-through methods slipped through at 4.76 kN (1,069 lbf) and 11.29 kN (2,538 lbf), respectively. We only did a single sample for both of these tests as the slip through values were too low to even consider recommending. The 5 and 6 pass-through methods had better results:

Results - 5-slot

Sample 1 - 24.81 kN (5,576 lbf)

Sample 2 - 21.62 kN (4,860 lbf)

Sample 3 - 19.29 kN (4,336 lbf)

Average - 21.90 kN (4,924 lbf)

Standard Deviation - 2.77 kN (622 lbf)

Five pass-through results

Results - 6-slot

Sample 1 - 31.73 kN (7,132 lbf)

Sample 2 - 31.17 kN (7,007 lbf)

Sample 3 - 30.60 kN (6,878 lbf)

Average - 31.17 kN (7,006 lbf)

St. Dev. - 0.56 kN (126 lbf)

All samples pulled through on the 3, 4, and 5 slot weaves. The method at which they pulled through was quite interesting. The first slippage always happened lower than the peak force in the test. It wasn't until the sling slipped considerably, likely melting fibers together, that it finally broke at the above values.

The 6-slot weave performed fantastic! It broke just below where this webbing breaks in a weblock and broke at the 5th slot that was woven. This is by far the best way to make an end loop in this material, particularly if you need one that is adjustable in length. Here is a video on how to do one of these loops:

Test 5 - Woven End Loop - With Stopper Knots

As a variation of the above tests, we decided to try woven end loops with stopper knots. We tried 3 different configurations of the woven end loop with stopper knots:

- A woven end loop with just 3 pass-throughs and a stopper

Woven end loop with 3 pass-throughs and a stopper knot

- A woven end loop with 4 pass-throughs and a stopper

Woven end loop with 4 pass-throughs and a stopper knot

- A woven end loop with 5 pass-throughs and a stopper

Woven end loop with 5 pass-throughs and a stopper knot

We only tested a single sample on the 3 pass-through method. It broke at 23.6 kN (5,305 lbf) at the slot where the stopper knot was set (last woven slot). This value was low compared to our other samples in this configuration, so we decided to not do more than a single sample. Here is a video of the test:

Results - 4-slot

Sample 1 - 24.97 kN (5,613 lbf)

Sample 2 - 25.69 kN (5,775 lbf)

Sample 3 - 25.69 kN (5,775 lbf)

Average - 25.45 kN (5,721 lbf)

Standard Deviation - 0.42 kN (93 lbf)

Results - 5-slot

Sample 1 - 27.36 kN (6,150 lbf)

Sample 2 - 27.42 kN (6,162 lbf)

Sample 3 - 25.84 kN (5,809 lbf)

Average - 26.87 kN (6,040 lbf)

St. Dev. - 0.89 kN (200 lbf)

Both of these configurations broke at the slot where the stopper knot was (last woven slot). We saw pretty minimal gains by adding a 5th slot to the weave, so we have concluded that a 4-slot weave with a stopper knot is more than adequate for most needs where an adjustable end loop is needed.

Test 6 - Brummel End Loop

Similar to hollow braid ropes, you can form a brummel splice with the Adjustable Anchor Webbing. To do this, simple pass one end through a slot that is a few slots from the end, then take the other end and pass it through a slot in that strand you passed through previously. This forms a sort of lock in a very small footprint that gives a usable end loop. There is a method to weave this if you only have access to one end as well, which can be quite handy. Here is a video on the methods:

Brummel End Loop


Sample 1 - 26.69 kN (6,000 lbf)

Sample 2 - 26.36 kN (5,925 lbf)

Sample 3 - 24.95 kN (5,609 lbf)

Average - 26.00 kN (5,845 lbf)

Standard Deviation - 0.92 kN (207 lbf)

Brummel end loop results

These all failed at the end slot where the second pass-through occurs. In my opinion, this method of usage is the way to go for any type of end loop. It's fast to rig, easy to setup, takes minimal length, and is quite strong, even in vertical pull.

Test 7 - Woven Loop - No Stopper Knots

Similar to the woven end loop, it's also possible to weave the ends together to form a continuous closed loop. To rig this, you have to pass both ends of the sling back through the other end 5 times, for a total of 10 weaves. Theoretically, this is a great way to form a continuous sling, but it takes quite a bit of material to make.

Woven Loop


Sample 1 - 24.69 kN (5,521 lbf)

Sample 2 - 29.64 kN (6,662 lbf)

Sample 3 - 27.99 kN (6,291 lbf)

Average - 27.99 kN (6,168 lbf)

Standard Deviation - 2.52 kN (565 lbf)

I am not fond of this rigging technique. As we can see from the above results, they don't even beat the single line strength of the Adjustable Anchor Webbing in a weblock. That's less than 50% strength retention! If you need a continuous loop of this material, I'd strongly recommend the Grog Loop shown below.

Test 8 - Woven Loop - With Stopper Knots

As a variation on the above test, based on our findings with using stopper knots on woven end loops, we decided to do a woven loop with stopper knots. We only did a single variation on this with 4-slots woven per end and a stopper on each end.

Woven continous loop with 4 pass-throughs per end and stopper knots


Sample 1 - 50.07 kN (11,256 lbf)

Sample 2 - 52.04 kN (11,697 lbf)

Sample 3 - 53.37 kN (11,997 lbf)

Average - 51.83 kN (11,650 lbf)

Standard Deviation - 1.66 kN (372 lbf)

Wow, what a difference stopper knots make! It seems that this type of configuration can definitely be safely used as long as you have stopper knots in place. I would say if you want supreme confidence in your continuous loop, go with 6 weaves and a stopper knot at the end. Here is a video on how to rig one of these loops:

Test 9 - Grog Loop

As with the Brummel End Loop, the Grog Loop is based off of a splicing technique used on hollow-braid ropes. This involves passing the two ends of the sling through each other one time, then weaving it back on itself. It differs from the woven loop above in that each end is woven on itself rather than the other end. We used 5 weaves per end, for a total of 10 weaves. Here is a video on how to tie it:

Grog Loop


Sample 1 - 51.05 kN (11,476 lbf)

Sample 2 - 56.31 kN (12,658 lbf)

Sample 3 - 57.57 kN (12,941 lbf)

Average - 54.98 kN (12,359 lbf)

Standard Deviation - 3.46 kN (777 lbf)

Grog Loop Results

All of these samples had a clean break outside of the woven areas. This the way it should be! Now, we have a solid continuous loop technique that rivals a purple spanset in strength and can be whatever length you want it to be! Imaine this sling in basket form or as a sliding-x between many points? Absolutely bomber!

We also tested a version of the Grog Loop with just 3 and 4 weaves per end, here are the results:

3-weave Results

Sample 1 - 40.54 kN (9,113 lbf)

Sample 2 - 38.32 kN (8,613 lbf)

Sample 3 - 37.74 kN (8,484 lbf)

Average - 38.87 kN (8,7379 lbf)

Standard Deviation - 1.48 kN (331 lbf)

4-weave Results

Sample 1 - 42.74 kN (9,608 lbf)

Sample 2 - 42.02 kN (9,446 lbf)

Sample 3 - 39.35 kN (8,846 lbf)

Average - 41.37 kN (9,300 lbf)

Standard Deviation - 1.78 kN (401 lbf)


As a general rule, for end loops, a Brummel or a woven end loop with at least 4 pass-throughs and a stopper knot will be the way go. If you want supreme strength, go with 6 pass-throughs and a stopper knot. If you need a strong continuous loop, use a Grog Loop or a woven loop with at least 4 pass-throughs on each strand and stopper knots on both. Otherwise, stick to clipping the various slots in whatever configuration you need.

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